First Science Results from the LUX Experiment

Daniel McKinsey, LUX Co-Spokesperson, Richard Gaitskell, LUX Co-Spokesperson, Brown University on behalf of the LUX Collaboration http://luxdarkmatter.org

Sanford Underground Research Facility

OctoberS 30, 2013

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 1 Composition of the Universe

The Higgs particle has been discovered, the last piece of the Standard Model.

But as successful as it has been, the Standard Model describes only 5% of the universe. The remaining 95% is in the form of dark energy and dark matter, whose fundamental nature is almost completely unknown.

Image: X-ray: NASA/CXC/CfA/M.Markevitch et al.; www.quantumdiaries.org Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.

LUX Dark Matter Experiment / Sanford Lab 2 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 2 Evidence for Dark Matter

Galaxy rotation curves The cosmic microwave background

www.quantumdiaries.org

Image: ESA and the Planck collaboration Gravitational lensing • 27% of the energy composition of the universe • Properties: • Stable and electrically neutral • Non-baryonic • Non-relativistic • Estimated local density: 0.3±0.1GeV·cm-3 • Candidates: WIMPs, axions, dark photons,...

Colley, Turner, Tyson, and NASA

LUX Dark Matter Experiment / Sanford Lab 3 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 3 Weakly Interacting Massive Particles (WIMPs)

A new particle that only very weakly interacts with ordinary matter could form Cold Dark Matter - Formed in massive amounts in the Big Bang. - Non-relativistic freeze-out. Decouples from ordinary matter. - Would exist today at densities of about 1000/m3.

Supersymmetry provides a natural candidate – the neutralino. - Lowest mass superposition of photino, zino, higgsino - Mass range from the proton mass to thousands of times the proton mass. - Wide range of cross-sections with ordinary matter, from 10-40 to 10-50 cm2. - Charge neutral and stable!

Universal Extra Dimensions: predicts stable Kaluza-Klein (KK) particles - Similar direct detection properties as neutralino - Distinguishable from neutralinos at accelerators

LUX Dark Matter Experiment / Sanford Lab 4 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 4 WIMP Direct Detection

Look for anomalous nuclear recoils in a low-background detector. R = N ρ σ . From = 220 km/s, get order of 10 keV deposited.

Requirements: •Low radioactivity •Low energy threshold •Gamma ray rejection •Scalability •Deep underground laboratory

LUX Dark Matter Experiment / Sanford Lab 5 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 5 Current WIMP Cross-section Limits SuperCDMS Soudan CDMS-lite SuperCDMS Soudan Low Threshold XENON 10 S2 (2013) 10!39 CDMS-II Ge Low Threshold (2011) 10!3 CoGeNT PICO250-C3F8 !40 (2012) !4 10 CDMS Si 10 (2013)

# ! ! 41 5 # 2 10 DAMA SIMPLE (2012) 10

COUPP (2012) pb cm !

! !42 CRESST !6 10 ZEPLIN-III (2012) 10 SuperCDMS !43 CDMS II Ge (2009) !7 10 EDELWEISS (2011) 10 SNOLAB SuperCDMS Soudan section section N EU TR Xenon100 (2012) !44 IN DarkSide 50 !8 10 O 10 7Be C TT LUX OHE SCA ER cross cross R NT I Neutrinos E 8 N !45 B G PICO250-CF3I !9 10 Neutrinos 10 Xenon1T

!46 DEAP3600 !10 10 DarkSide G2 10 LZ nucleon nucleon

! ! !47 !11 10 (Green&ovals)&Asymmetric&DM&& 10 (Violet&oval)&Magne7c&DM& RING ATTE !48 (Blue&oval)&Extra&dimensions&& NT SC !12

E WIMP HER WIMP 10 (Red&circle)&SUSY&MSSM& CO 10 RINO &&&&&MSSM:&Pure&Higgsino&& NEUT !49 !13 10 &&&&&MSSM:&A&funnel& Atmospheric and DSNB Neutrinos 10 &&&&&MSSM:&BinoEstop&coannihila7on& !50 &&&&&MSSM:&BinoEsquark&coannihila7on& !14 10 & 10 1 10 100 1000 104 WIMP Mass GeV c2

LUX Dark Matter Experiment / Sanford Lab 6 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 6 ! " # Two-phase Xenon WIMP Detectors

Z position from S1 – S2 timing X-Y positions from S2 light pattern Excellent 3D imaging (~mm resolution) - eliminates edge events - rejects multiple scatters Gamma ray, backgrounds reduced by self-shielding

Reject gammas, betas by charge (S2) to light (S1) ratio. Expect > 99.5% rejection.

LUX Dark Matter Experiment / Sanford Lab 7 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 7 The LUX Detector

Thermosyphon

Copper shield

Water tank Top PMT array

Anode grid

PTFE reflector panels and field cage Low-radioactivity Titanium Cryostat Cathode grid 370 kg total xenon mass 250 kg active liquid xenon Bottom PMT array 118 kg fiducial mass

LUX Dark Matter Experiment / Sanford Lab 8 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 8 LUX Benefits from an Exceptional Lab and Exceptional Lab Support

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 9 The LUX Collaboration: ~100 researchers from 17 institutions

Collaboration Meeting, Brown Sanford Lab, April 2013 SD School of Mines Richard Gaitskell PI, Professor Simon Fiorucci Research Associate Xinhua Bai PI, Professor Monica Pangilinan Postdoc Tyler Liebsch Graduate Student Jeremy Chapman Graduate Student Doug Tiedt Graduate Student David Malling Graduate Student James Verbus Graduate Student Samuel Chung Chan Graduate Student SDSTA Dongqing Huang Graduate Student David Taylor Project Engineer Mark Hanhardt Support Scientist Case Western

Thomas Shutt PI, Professor Texas A&M Dan Akerib PI, Professor Karen Gibson Postdoc James White † PI, Professor Tomasz Biesiadzinski Postdoc Robert Webb PI, Professor Wing H To Postdoc Rachel Mannino Graduate Student Adam Bradley Graduate Student Clement Sofka Graduate Student Patrick Phelps Graduate Student Chang Lee Graduate Student UC Davis Kati Pech Graduate Student Mani Tripathi PI, Professor Imperial College London Bob Svoboda Professor Richard Lander Professor Henrique Araujo PI, Reader Britt Holbrook Senior Engineer Tim Sumner Professor John Thomson Senior Machinist Alastair Currie Postdoc Ray Gerhard Electronics Engineer Adam Bailey Graduate Student Aaron Manalaysay Postdoc Matthew Szydagis Postdoc Lawrence Berkeley + UC Berkeley Richard Ott Postdoc Bob Jacobsen PI, Professor Jeremy Mock Graduate Student Murdock Gilchriese Senior Scientist James Morad Graduate Student University of Edinburgh University of South Dakota Kevin Lesko Senior Scientist Nick Walsh Graduate Student Dongming Mei PI, Professor Carlos Hernandez Faham Postdoc Michael Woods Graduate Student Alex Murphy PI, Reader Chao Zhang Postdoc Victor Gehman Scientist Sergey Uvarov Graduate Student Paolo Beltrame Research Fellow Angela Chiller Graduate Student Mia Ihm Graduate Student Brian Lenardo Graduate Student James Dobson Postdoc Chris Chiller Graduate Student Dana Byram *Now at SDSTA Lawrence Livermore University of Maryland UC Santa Barbara Adam Bernstein PI, Leader of Adv. Detectors Group Carter Hall PI, Professor Harry Nelson PI, Professor Yale Dennis Carr Mechanical Technician Attila Dobi Graduate Student Mike Witherell Professor Kareem Kazkaz Staff Physicist Richard Knoche Graduate Student Daniel McKinsey PI, Professor Dean White Engineer Peter Sorensen Staff Physicist Jon Balajthy Graduate Student Peter Parker Professor Susanne Kyre Engineer John Bower Engineer Sidney Cahn Lecturer/Research Scientist Carmen Carmona Postdoc Ethan Bernard Postdoc Curt Nehrkorn Graduate Student University of Rochester Markus Horn Postdoc LIP Coimbra Scott Haselschwardt Graduate Student Blair Edwards Postdoc Frank Wolfs PI, Professor Isabel Lopes PI, Professor Scott Hertel Postdoc University College London Wojtek Skutski Senior Scientist Jose Pinto da Cunha Assistant Professor Kevin O’Sullivan Postdoc Eryk Druszkiewicz Graduate Student Vladimir Solovov Senior Researcher Nicole Larsen Graduate Student Chamkaur Ghag PI, Lecturer Mongkol Moongweluwan Graduate Student Luiz de Viveiros Postdoc Evan Pease Graduate Student Lea Reichhart Postdoc Alexander Lindote Postdoc Brian Tennyson Graduate Student Francisco Neves Postdoc Ariana Hackenburg Graduate Student Claudio Silva Postdoc Elizabeth Boulton Graduate Student LUX Dark Matter Experiment / Sanford Lab 10 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 10 In Memoriam – Dr. James White

A key innovator in xenon dark matter detector technology, a creator of LUX, and a dearly missed colleague

LUX Dark Matter Experiment / Sanford Lab 11 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 11 LUX – the Instrument

LUX Dark Matter Experiment / Sanford Lab 12 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 12 LUX Construction

LUX Dark Matter Experiment / Sanford Lab 13 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 13 LUX – Supporting Systems

Xenon gas handling and sampling Thermosyphon Xe storage and recovery cryogenics

LN bath

conduits Cathode HV feedthrough into cold water head tank

LUX Thermosyphon

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 14 LUX Timeline

LUX funded in 2008 by DOE and NSF

Above-ground laboratory completed at SURF in 2011 LUX assembled; above-ground commissioning runs completed

Underground laboratory completed at SURF in 2012. LUX moves underground in July to its new home in the Davis cavern.

Detector cooldown and gas phase testing completed early February 2013

Xenon condensation completed mid February 2013

Detector commissioning completed April 2013

Initial (3-month) WIMP search. First results presented today!

Full year-long WIMP search to begin in 2014. Result in 2015

LUX Dark Matter Experiment / Sanford Lab 15 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 15 LUX Has Exceptional Technical Performance

Low-energy electron recoil rate of

3e-3 events/keV/kg/day. Electron lifetime (microseconds)

Electron drift length (cm) Kr/Xe ratio of 3.5 ppt.

Electron drift length longer than 130 cm.

Light detection efficiency of 14%.

Electron recoil discrimination of 99.6%, with drift field of 181 V/cm.

Days since March 1, 2013

LUX Dark Matter Experiment / Sanford Lab 16 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 16 LUX installed in its water tank shield, a mile underground at SURF

LUX Dark Matter Experiment / Sanford Lab 17 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 17 Typical Event in LUX

1.5 keV gamma ray scattering event

LUX Dark Matter Experiment / Sanford Lab 18 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 18 XYZ Position Reconstruction

Z coordinate is determined by the time between S1 and S2 (electron drift speed of 1.51 mm/microsecond)

Light Response Functions (LRFs) are found by iteratively fitting the distribution of S2 signal for each PMT.

XY position is determined by fitting the S2 hit pattern relative to the LRFs.

Reconstruction of XY from events near the anode grid resolves grid wires with 5 mm pitch.

LUX Dark Matter Experiment / Sanford Lab 19 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 19 Kr-83m Calibration •Rb-83 produces Kr-83m when it decays; this krypton gas can then be flushed into the LUX gas system to calibrate the detector as a function of position. •Provides reliable, efficient, homogeneous calibration of both S1 and S2 signals, which then decays away in a few hours, restoring low-background operation..

Kr-83m source (Rb-83 coated on charcoal, within xenon gas plumbing)

LUX Dark Matter Experiment / Sanford Lab 20 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 20 Kr-83m Calibration

•Over 1 million Kr-83m events, spread uniformly through the detector.

Fiducial volume determination Position-based S1 corrections

LUX Dark Matter Experiment / Sanford Lab 21 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 21 Tritiated Methane Calibration

•LUX uses tritiated methane, doped into the detector, to accurately calibrate the efficiency of background rejection. •This beta source (endpoint energy 18 keV) allows electron recoil S2/S1 band calibration with unprecedented accuracy •The tritiated methane is then fully removed by circulating the xenon through the getter •Parametrization of the electron recoil band from the high-statistics tritiated methane data is then used to characterize the background model.

LUX Dark Matter Experiment / Sanford Lab 22 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 22 Electron Recoil and Nuclear Recoil Bands

Tritium provides very high statistics electron recoil calibration (200 events/phe) Neutron calibration is consistent with NEST + simulations

Gray contours indicate constant energies using a S1-S2 combined energy scale

LUX Dark Matter Experiment / Sanford Lab 23 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 23 Electron Recoil Discrimination

Average discrimination from 2-30 S1 photoelectrons measured to be 99.6% (with 50% nuclear recoil acceptance) −1 10 90%

−2 10 99%

−3

10 99.9% discrimination leakage fraction

−4 10 99.99% 0 5 10 15 20 25 30 S1 x,y,z corrected (phe) Black circles show leakage from counting events from the dataset Red circles show projections of Gaussian fits below the nuclear recoil band mean

LUX Dark Matter Experiment / Sanford Lab 24 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 24 Data 35 2:20:25 PM 10/28/13 8

7

6 0.3 19.3 LUX 2013 5 Aprile 2013

0.25 16.1 (photons/keV) yield absolute Aprile 2011 Data 35 2:20:25 PM 10/28/13 4 Plante 2011 9.2 0.2 2013 LUX 12.9 Horn 2011a 3 Horn 2011b Manzur 2010 0.15 9 9.7 2 ! NEST: 0.1 8.8 6.4 1 Light and Charge Yields in LUX Zero field Data 35 2:20:25 PM 10/28/13

yield relative to Co-57 gamma 181 V/cm 0.05 8.6 3.2 08 ! •Modeled Using Noble Element Simulation Technique-0.0015 (NEST).-0.001 Data-0.0005 35 2:20:250 PM 10/28/130.0005 0.001 0.0015

•NEST based0 on canon of existing experimental Zero field 8.478 data. 0 1 10 100 J •Artificial cutoff in light andnuclear charge recoil yields energy assumed (keV) below 3 keVnr, to be conservative. 67 •Includes predicted electric field quenching of light8.2 signal, to 77-82% of the zero field light yield

0.3 19.3 LUX 2013 56 8 Aprile 2013 LUXAprile 2013 2011 5

0.25 16.1 (photons/keV) yield absolute 4 Data 35 2:20:25AprilePlante PM 10/28/13 20132011 7.8 LUX 2013 LUX AprileHorn 2011a 2011 9.2 0.2 4-0.0015 -0.001 12.9-0.0005 0 PlanteHorn0.0005 2011b 2011 0.001 0.0015 3

LUX 2013 LUX HornManzur 2011a 2010 9 J Horn 2011b 0.15 23 9.7 Manzur 2010 NEST:! 8.82 0.1 1 6.4 Zero field 1 181 V/cm yield relative to Co-57 gamma 0.05 8.60 3.2 -0.0015 -0.001 -0.0005 0 0.0005 0.001 0.0015 0 0 Zero field -0.00158.4 -0.001 0 -0.0005 0J 0.0005 0.001 0.0015 1 10 100 nuclear recoil energy (keV) J 8.2 LUX Dark Matter Experiment / Sanford Lab 25 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 25 8

7.8 -0.0015 -0.001 -0.0005 0 0.0005 0.001 0.0015

J The center of LUX, measured at low energies, is the radioactively quietest place in the world.

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 26 Total Electron Recoil Event Rate <5 keVee

log10 evts/keVee/kg/day

118 kg 3.1+/-0.2 mdru (0.5 dru cosmogenic)

r<18 cm z=7-47 cm

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 27 And it continues to get quieter - Xe Cosmogenic Activity cools (rate in 44 days)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 28 How Quiet is it in the LUX Detector?

When we ran it above ground the energy being deposited in the detector can be though of as: Standing in the middle of the Super Bowl at the start of a game and listening to the noise generate by 75,000 people clapping for their team (twice a second)

Once we took LUX underground the energy deposited by backgrounds in the inner Fiducial Volume at the center of the detector becomes:

Listening to one person clapping from the stands every 1 minute

The WIMP signal is even lower energy: It is like listening for someone taking the occasional a breath

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 29 4850ft Depth Reduces Muon Flux by 3 million •At Sanford Lab LUX’s first run we don’t have to worry about signals from subterranean muons

Comparison(of(Laboratory(Sizes((

0$

!1000$

!2000$

!3000$

!4000$

!5000$

!6000$ Laboratory(Depth((MWE)( !7000$

!8000$

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 30 LUX High Energy Gamma Background in 220 kg •Full gamma Spectrum, excluding region ±2 cm from top/bottom grids

0 10 127Xe 214Pb (238U) 228Ac (232Th) 214Bi (238U) 60Co 40K 208 232 −1 Tl ( Th) 10 214 238 Bi ( U) + 60Co

/ kg day Data ee

−2 10 Full Simulation Model cts / keV

−3 10 500 1000 1500 2000 2500 3000 Energy deposited [keV ] ee

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 31 Background Summary for 118 kg Fiducial •Average levels over period April-August WIMP Search Run

Background Component Source 10-3 x evts/keVee/kg/day

Internal Components including Gamma-rays PMTS (80%), Cryostat, Teflon 1.8±0.2stat±0.3sys

127 Cosmogenic Xe (36.4 day half-life) 0.5±0.02stat±0.1sys 0.87 -> 0.28 during run

214 Pb 222Rn 0.11-0.22(90% CL)

85 Reduced from Kr 0.13±0.07sys 130 ppb to 3.5±1 ppt

Predicted Total 2.6±0.2stat±0.4sys

Observed Total 3.1±0.2stat

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 32 Full Background Model Fits ER Data Over Entire Range

0 10 127 Xe (36.4 day half-life) Gamma-rays from −1 10 residual internal activity

−2 10 ee

DRU −3 214 10 Pb

−4 10 85Kr

0 500 1000 1500 2000 2500 3000 Energy deposited [keV ] ee

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 33 127Xe Electron Capture - Simulation •x-ray line emission in center of detector following full escape of gamma associated with nuclear excited state

ER PDF (131019c2) − norm sum(19.7) − compare to WS 88d x 118kg (Gaitskell) 3 −0.5 Probability Density Function −1

2.5 1 keVee −1.5

−2 2 5 keVee −2.5

−3 1.5 log10(S2bc/s1c) −3.5

−4 1 0.2 keVee −4.5

0.5 −5 0 5 10 15 20 25 30 35 40 S1c (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 34 LUX WIMP Search Summary - How did you spend your summer? •April 21 - August 8, 2013 - 110 calendar days ◆85.3 live days of WIMP Search ◆118.3+/-6.5 kg fiducial mass

•Calibrations ◆Frequent injected 83mKr calibration to correct for any S1 or S2 gain shifts ◆AmBe&Cf calibrations+Sims to define NR band ◆Injected Tritiated Methane defines full ER band at all relevant energies

•Efficiency ◆Efficiency for WIMP event detection was studied using data from calibration sets using multiple techniques and all were all shown to be consistent with one another

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 35 “The Sensitivity of a Dark Matter Experiment Scales as its Mass”

“The problems scale as its Surface Area”

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 36 LUX WIMP Search Summary /2 •Data Analysis and Blinding Discussion ◆The Xe Target inner fiducial volume is very simple, it sits inside a larger volume of Xe with only a “virtual” surface dividing them • Modeling of extrinsic and intrinsic background signals in large monolithic Xe volume has low systematics ◆No blinding was imposed for the first WIMP data analysis • We aimed to apply minimum set of cuts in order to reduce any tuning of event cuts/acceptance. • The cuts list is very short ... ◆Fiducial Volume was selected based on requirement to keep low energy events from grid and teflon surface out of WS data. Primarily alpha-decay events. • Low energy alpha-parent nuclear recoil events generate small S2 + S1 events. Studies position reconstruction resolution. Tested using data outside WIMP search S1 energy range. This ensured that position reconstruction for sets were similar, and definition of fiducial was not biased. ◆Use of Profile Likelihood Ratio (PLR) analysis means we don’t have to draw acceptance boxes • This avoids potential bias in data analysis from selecting regions in S1,S2 signal-space ◆Inputs for Profile Likelihood Ratio analysis were developed using high statistics in situ calibrations, with some simulations to cross check

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 37 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial •~11.5 Hz of S2-like triggers ◆>99% efficiency for events S2area>200 phe

keVnr = keV nuclear recoil keVee = keV electron equivalent LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 38 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial • <0.8% of run time lost to instabilities

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 39 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 40 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial •Primary method of defining energy range of analysis ◆Note S1 analysis threshold of S1area >=2 phe. Expected S1 for a 3 keVnr event is 1.94 phe. ◆This threshold is very low, and provides high sensitivity over full WIMP mass range

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 41 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial •Low energy efficiency is dominated by S1 acceptance ◆S2 area cut is looser constraint on WIMP energy range

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 42 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial •The aftermath of large S2 events in the detector can lead to additional single electron events, for periods ~0.1-1 ms afterwards ◆ Events that coincide with periods of non-quiescence can be cut by simply demanding <4 extracted electron events (<100 phe) of spurious signal occurs during +/-0.5 ms around the primary S1 and S2 event ◆ This cut causes < 0.8% dead time

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 43 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial

◆Events from residual radioactivity on cathode and gate grids lead to significant number of events in energy region of interest. Use a simple drift time cut to remove them.

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 44 Event & Cuts Summary: 85 live days

Cut Explanation Events Remaining

All Triggers S2 Trigger >99% for S2raw>200 phe 83,673,413 Detector Stability Cut periods of excursion for Xe Gas Pressure, Xe 82,918,901 Liquid Level, Grid Voltages Single Scatter Events Identification of S1 and S2. Single Scatter cut. 6,585,686 S1 energy Accept 2-30 phe 26,824 (energy ~ 0.9-5.3 keVee, ~3-18 keVnr) S2 energy Accept 200-3300 phe (>8 extracted electrons) 20,989 Removes single electron / small S2 edge events S2 Single Electron Quiet Cut Cut if >100 phe outside S1+S2 identified 19,796 +/-0.5 ms around trigger (0.8% drop in livetime) Drift Time Cut away from grids Cutting away from cathode and gate regions, 8731 60 < drift time < 324 us Fiducial Volume radius and drift cut Radius < 18 cm, 38 < drift time < 305 us, 160 118 kg fiducial •Define a Fiducial Volume of 118 kg using combination of radius and drift time cut ◆ Low energy alpha-parent nuclear recoil events generate small S2 + S1 events. The radius and drift time cuts were set using population of events which had S1’s outside of the WIMP signal search range, but with S2’s of a comparable size to lower S1 events in same population. This ensured that position reconstruction for sets were similar, and definition of fiducial was not biased. •Cuts also remove corner regions where ER event rates are proportionally very high LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 45 S1 Efficiency For WIMP Detection

• S1 efficiency was studied in detail using — AmBe NR calibration — Tritiated-Methane calibration — Full Monte Carlo sim of NR events (S1+S2 processed by same analysis chain) • Overall efficiency is dominated by S1 efficiency, compared to S2 efficiency (see supporting slides) 2 o LUX AmBe Neutron Calibration S1 data (lhs) 1.8 2 – Monte Carlo S1 LUXSim/NEST (lhs) 10 1.6 gray & red Efficiency from AmBe data 1.4 1.2 1 1 10 0.8 Efficiency from LUX Tritium data, applied to ER background model for PLR 0.6

relative differential rate Flat energy source nuclear recoil sims, 0.4

applied to WIMP signal model for PLR relative detection efficiency 0 0.2 10 0 0 1 2 10 10 10 S1 x,y,z corrected (phe) LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 46 WIMP Detection Efficiency - True Recoil Energy

3 keVnr S2area ~230 phe (8.9 extracted electrons) Efficiency falls >18 keVnr due S1area ~2.0 phe S1 [2,30] phe range

1 0.9 7.5 keVnr >95% 0.8 0.7 0.6 Before any analysis cuts: 0.5 S1 pulse identification 4.3 keVnr 50% S2 pulse identification efficiency 0.4 S1+S2 singles identification 0.3 0.2 3 keVnr 17% Including analysis cuts: 0.1 Efficiency for S1+S2 identification 0 ( S1area>2 phe, S2area>200 phe )

0 2 4 6 8 10 12 14 16 18 20 recoil energy (keV ) nr True Recoil Energy equivalence based on LUX 2013 Neutron Calibration/NEST Model

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 47 Simulated WIMP Signals for 85 days, 118 kg •Pick a mass of 1000 GeV and cross section at the existing XENON100 90% -44 WS2 from PDF (131018) (Currie/Gaitskell) CL Sensitivity 1.9x10 cmmW =- 1000.0 Would GeV cs expect= 1.5e−44 cm2 9 n WIMPs= 7 in LUX Search 2.5 −2 Probability Density

Function (PDF) for WIMP −2.5

2 Signal using in PLR Conservatively −3 assume no signal

generated for 1.5 −3.5 recoils < 3 keVnr

to reflect lowest log10(S2bc/s1c) energy for which −4 NR calibration is 1 available. 10-90% Nuclear Recoil Band −4.5

0.5 −5 0 5 10 15 20 25 S1c (phe) ◆PDF assumes Standard Milky Way Halo parameters as described in Savage, Freese, Gondolo 2 (2006) v0=220 km/s, vescape = 544 km/s, ρ0 = 0.3 GeV/c , vearth = 245 km/s • Helm Form Factor.

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 48 Simulated WIMP Signals for 85 days, 118 kg •At a mass of 8.6 GeV and cross section favored CDMS II Si (2012) cross

section 2.0x10-41 cm2 - ExpectWS from PDF 1550 (131018) WIMPs (Currie/Gaitskell) in LUX Search mW = 8.6 GeV cs = 2.0e−41 cm2 n = 1545 2.5 −2 Note how WIMP distribution appear below the calibration −2.5 NR mean ... 2

−3 Conservatively

assume no signal 1.5 −3.5 generated for

recoils < 3 keVnr log10(S2bc/s1c) to reflect lowest −4 energy for which 1 ... the shift occurs because for a given S2 value NR calibration is the S1 is more likely to have up-fluctuated in order −4.5 available. to appear above threshold

0.5 −5 0 5 10 15 20 25 S1c (phe)

◆The shift in the WIMP PDF downwards improves the effective ER event leakage fraction

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 49 LUX WIMP Search, 85 live-days, 118 kg • Electron Recoil and Nuclear Recoil Bands 2.6

2.4

2.2

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 50 LUX WIMP Search, 85 live-days, 118 kg •Event energies in keVee and keVnr

1.3 keV 2.6 ee

2.4 1.8

2.2

2 3.5 4.6 1.8 5.9 7.1 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

3 6 9 12 15 18 21 24 27 30 keV 1 nr 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 51 LUX WIMP Search, 85 live-days, 118 kg

2.6

2.4

2.2

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 52 LUX WIMP Search, 85 live-days, 118 kg •S1area >= 2 phe analysis threshold. S1area <= 30 phe 2.6 S1 2 phe selected as S1 30 phe selected conservative lowest early in analysis in 2.4 threshold for which S1 order to stay below pulse identification showed 127Xe 5 keVee 2.2 >50% acceptance cosmogenic peak

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 53 LUX WIMP Search, 85 live-days, 118 kg •Total S2area >= 200 phe analysis threshold. 2.6 Note cut is made in raw S2 area, rather than corrected S2 area. 2.4 Additionally plots shows S2b signal measured by just bottom array of PMTs. Reduces any 2.2 systematic associated with 2 PMT that are off in top array 2 So line shown in this plot is indicative of cut 1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 54 LUX WIMP Search, 85 live-days, 118 kg

2.6

2.4

2.2

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 55 LUX WIMP Search, 85 live-days, 118 kg

2.6 160 events observed 1.9 events/day 2.4

2.2

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 56 LUX WIMP Search, 85 live-days, 118 kg

2.6 160 events observed 1.9 events/day 2.4 Distribution of events is completely consistent with ER calibration PDF and 4 component 2.2 background model determined from fits to 2 position dependent background spectra

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 57 LUX WIMP Search, 85 live-days, 118 kg

1.3 keV 2.6 ee

2.4 1.8

2.2

2 3.5 4.6 1.8 5.9 7.1 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2 Event distribution from 3 6 9 12 15 18 21 24 27 30 keV 5 keVee from 127Xe nr 1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 58 LUX WIMP Search, 85 live-days, 118 kg

2.6 Profile-Likelihood Analysis shows a 2.4 p-value of 35% consistent with ER background and no WIMP signal 2.2

2

1.8 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

1 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 59 LUX WIMP Search, 85 live-days, 118 kg

1.3 keV 2.6 ee Profile-Likelihood Ratio used to determine 2.4 1.8 nWIMP 90% CL upper limit Value ranges from 2.4 events at low mass to 2.2 5.3 events at highest masses

2 3.5 4.6 1.8 5.9 7.1 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

3 6 9 12 15 18 21 24 27 30 keV 1 nr 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 60 LUX WIMP Search, 85 live-days, 118 kg

1.3 2.6 keV ee 2.4 2.4 2.2

3.5 2

1.8 /S1) x,y,z corrected

b 1.6

(S2 1550 low mass WIMP events? 10 1.4 log

1.2 12

keV 36 9 1 nr 0 5 10 15 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 61 LUX WIMP Search, 85 live-days, 118 kg

1.3 keV 2.6 ee ER Calibration 99.6±0.1% leakage below NR mean, so expect 0.64 +/- 0.16 for 160 events 2.4 1.8

2.2

2 3.5 4.6 1.8 5.9 7.1 /S1) x,y,z corrected b 1.6 (S2

10 1.4 log

1.2

3 6 9 12 15 18 21 24 27 30 keV 1 nr 0 10 20 30 40 50 S1 x,y,z corrected (phe)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 62 Spin Independent Sensitivity Plots Edelweiss II ZEPLIN III )

2 CDMS II Ge

XENON100(2011)-100 live days −44 10 XENON100(2012)-225 live days

−45 10 LUX (2013)-85 live days WIMP − nucleon cross section (cm LUX +/-1σ expected sensitivity

1 2 3 10 10 10 m (GeV/c2) WIMP

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 63 Spin Independent Sensitivity Plots

−40

) 10 2

−41 10

−42 10

−43 10

−44 10 WIMP − nucleon cross section (cm

−45 10

1 2 3 10 10 10 m (GeV/c2) WIMP

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 64 Low Mass WIMPs - Fully excluded by LUX

CDMS II Ge DAMA/LIBRA Favored )

2 −40 10 CoGeNT Favored CRESST Favored x −41 10 CDMS II Si Favored

−42 10

XENON100(2012)-225 live days

−43 10 >20x more sensitivity WIMP − nucleon cross section (cm

LUX (2013)-85 live days −44 LUX +/-1σ expected sensitivity 10 5 6 7 8 9 10 12 m (GeV/c2) WIMP LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 65 Projected LUX 300 day WIMP Search Run •We intend to run LUX for a new run of 300 days in 2014/15 ◆Extending sensitivity by another factor 5 ◆Even though LUX sees no WIMP-like ) events in the current run, it is still quite 2 −44 possible to discover a signal when 10 extending the reach ◆LUX does not exclude LUX

−45 LUX (2013)-85 live days •WIMPs remain our favored quarry 10

WIMP − nucleon cross section (cm x5 •LZ 20x increase in target mass LUX (2013)-300 live days ◆ −46 If approved plans to be deployed in 10 1 2 3 Davis Lab in 2016+ 10 10 10 m (GeV/c2) WIMP ◆(Talk by Tom Shutt)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 66 LUX Statistics

12,474 person-days on site at Sanford Lab so far ...

5.8 million feet travelled vertically

>1/2 million Wiki Page Reads (that is reading all of War and Peace every day for over a year)

We started to estimate the number of USPS employees that would have been employed to move the 2 million+ P2P email messages, if messages were still carried by conventional means ... but then we realized we had talks to write

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 67 Conclusion •LUX has made a WIMP Search run of 86 live-days and released the analysis + PRL submission within 9 months of first cooling in Davis Lab ◆Backgrounds as expected, inner fiducial ER rate <2 events/day in region of interest 83m ◆Major advances in calibration techniques including Kr and Tritiated-CH4 injected directly into Xe target ◆Very low energy threshold achieved 3 keVnr with no ambiguous/leakage events ◆ER rejection shown to be 99.6+/-0.1% in energy range of interest •Intermediate and High Mass WIMPs ◆Extended sensitivity over existing experiments by x3 at 35 GeV and x2 at 1000 GeV •Low Mass WIMP Favored Hypotheses ruled out ◆LUX WIMP Sensitivity 20x better ◆LUX does not observe 6-10 GeV WIMPs favored by earlier experiments •Thanks to: ◆DOE and NSF ◆Governor and State of South Dakota and Denny Sanford ◆Sanford Lab for all their support to get to this world-leading result

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 68 LUX Results Paper LUX Results Paper will be available at 10.15 am MT on http://sanfordlab.org http://luxdarkmatter.org

Will also be available on http://arXiv.org tonight. Paper has been submitted to PRL

Welcome to Club Sub Zepto (*)

LUX is the first WIMP detector to reach below a zeptobarn cross section * zeptobarn is 10-45 cm2 A barn is the size of barn door at nuclear scales!

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 69 LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 70 •SUPPORTING MATERIAL

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 71 NR Calibrations

Mean Width

• Above plots show comparisons between simulation (blue), the NEST prediction (black), and data for the mean and width of the nuclear recoil band from AmBe calibrations • The mean and width are different in the calibrations because the data contain ER contamination and neutron-X events, which are modeled well by the simulation

LUX Dark Matter Experiment / Sanford Lab 72 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 72 Position of Low Energy Events in 85 day Exposure

0 gate grid 50

s) 100 µ 150 200

drift time ( 250

300 wall face wall corner 350 cathode grid 0 100 200 300 400 500 600 radius2 (cm2)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 73 Cosmogenic Isotopes Decaying •127Xe Decay vs Time 131mXe Decay vs Time

16 3

14 2.5

2 12 1.5 10 1 counts / kg day counts / kg day 8 0.5

6 0 0 10 20 30 40 0 10 20 30 40 Time [days] Time [days]

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 74 AmBe S2 Calibration

2 10

1 10 differential rate

0 10

1 2 10 10 S2 x,y,z corrected (extracted electrons)

LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 75